Production of photographic diazotype prints



{Patented July 23, 1940 PRODUCTION on sr'no'roouarnre Q nmz o rm'rnmrs,

Werner, Paul Leiicli, London, England, assignor a to Eugene DietzgenCompany, New 10th,

No Drawing. Application October 25, 1934, 8

invention relates to the production. of

photographic diazotype prints and has ior ob- Ject to provideimprovements therein. In the productionof diamtype prints, three(compounds aregenerally used, namely: 1 (1) A diazo-salt which bleachesout when ex posedto light under a drawing.

. l (2) A coupling component capable of form- M ingan az'o-dyestufl withthe undecomposed diazobody.

commercialscale, namely:

f containingbotnthe diazo-body and the coupling component. In caseptobring about the development for the picture,after the ,paper has to thelight under a drawingonly thethird component namely, alkali, has ,tofbes I is generally done byexposing, the y print to theaction of ammoniafumes.

Kb) The paper is prepared with a solution-con taining the diazo -bodyonly (generally in. pres- {ence of an acid or acid salts) For thedevelop-; ment of this paper, ali'quid developer contain- I ing inaddition toiithelalkali, alsothecoupling component, has to be applied:in athin layer. Method ,(a) is generally described. as (the drydevelopment, process, and method (bJf-asrthe Ji d I, 0 ya" semi-drydevelopment process. Both-processes are on alargescale. 5

1 In papers prepared according,to fniethod fidi [only couple underalkalineconditionsff or else some 'p'rccess such as; acutedehydrationmust be employed to prevent the'coupling process taking aplace before development: and even ii. somesuch the diam bodieschos'enmust either be such that process is employed theldiazlo bodies chosenmust be bodies which react onlyl slowly in neutral or acid conditions.lphowever, have found that if ,thecoupling component ,isintroduced intothe "containing the diazo body, by dusting the coupling componentinpowder form over the film when dry,-II can use anydiazo body which is:not either a diazo-anhydride or which has notbasic substitutions whichare not neutralized by suitable negative substitutions (for instance,aminoacylamino a, compounds can be used and derivatives of thediphenylseries are particularlyusuitable, as well as those of the'di-and triphenyl- Alkali, orf'a substance having an alkaline reactionwhich permitsthecoupling to takeplace.

1 'I'hereare two methods by which thediazov H-typeiprocessghasbeencarried outso i'ar on a (a) paper is preparedwithja solution a o pe paper o te f a e itive e layer containing adiazo'compound that is ca- [-pabl'e oi'coupling in neutral or acidconditions;

phenolic coupling component in the light-sensi-I 1 Plinghas taken placepriorto the actual de;

velopment. 1 l l The object of the' presentinvention is to provide apaper which can be developedin a simpler and morefadvantageous manner,namely,

one which shows thejjiollowing ,fe'atures I The used! either the gaseousmethod'oi V developme'ntior the seini-drymethod for the same" paper.

- zxrne ama the use of hairpin;

kaline reacting substances 'i'or development; 1

1 3. The carrying out of. the gaseous method of development by"meanssimply oiwater Yvapour,

thus avoiding the use of ammonia "iumes. According to the presentinvention! prepare a u and which would not permit the inclusion ofthe',tive layer owing. to premature couplingitaking. 1

place. After sensitizing, anddrying, the paper is" then treated with acoupling componentjbysub-- j sequently dusting fit over with a finepowdercone I 1 taining either the coupling component alonefor i inadmixture. with other substances, thevuse which isfmore fully, describedlater. The paper, when readyfor. use, contains therefore the light-.-sensitive diazo substance in the coating, andal-j' 1,- so carries thecoupling component capable of forming a dyestufl with the undecomposeddiazo Aiter exposure tolight in the way, the print mayjbev developedsimply by the action 0Q water. Itijis 'particularlyadvantageous to usewaterioifjdevelopment in sucha way as not appreciably to' wet the paperso that development maybeicarried'out by the dry process as previouslydeflnedz' Thisfmay advantageously done by exposing the paper tosteam orother form oi water vapour. In order to develop the,

- print in reasonableume, it is of courseadvantageous to water vapour ina concentrated iorm, namely, in the-form of steam or water, vapourarising; from heated water.

"In addition to water vepour other methods can be used for developingthe print, and in particular other methods which do not appreciably wetthe paper. For example, insteadoi water vapour the paperlmayl he treatedwith a quick y moist acetone. I V

"Another method 01, dry development-by means drying liquid, such asmoistmethylated spirit, or Y oi water is tousera gelatine composition. Aflattray, plate or other support, of suitable dimenu I v kil ;containing ajelly formed ofjg'elatine'and,

water .is used and-the print, after exposure, is

pressed facedownwards; on to the jelly, The moisture in' the Jelly issufficient to ,bring rabout development in a few seconds; leavingadryprint'.

A Jelly of suitable composition is one containing 60 gramspf gelatlneand 20-30 cc. of glycerine in 500 cc. of water.

Development may also conveniently be carried ;out by utilizing theloosely combined moisture in ;a suitable hydrated salt,such as hydratedsodium sulphate. For example, hydrated sodium sulphate may beincorporated in the paper before coating, or it may be incorporated inthe lightachieved of obtaining a print which is practically sensitive,layer or it may be incorporated in the powder containing the couplingcomponent. In any. of these cases the exposed print is developed simplyby gentle heating which causes the hydrated salt to dissociate, so thatthe water vapour liberated brings about the developmental the print,which print is of course dry. p p

In any a of these ways the advantage is dry and which, owing totheabsence of wetting, preservesa sharp line. If, however, for anyreason-it is desired to use the semi-dry developing process, thismayalso be done by using an ordinary developing machine containing water.In

this case it may be found advantageous to add V 1a substance such as thesalt of a weakjacid with a strong base'either to the'sensitive layer orto the coupling component; a substance of this type v has the propertyof acting as a coupling acceler ator and-also its saline'nature' helpsto prevent the line from running? Altematively, instead e of using wateralone in the developing machine,

a substance which prevents the line from run "ning,' such as potassiumsulphate, or sodium chlorideor a substance whichnot only prevents theline from running" but also acts as a coupling accelerator, such assodium acetate, may

be dissolved in the water used for the developer. If it isdesiredtocarry out the development by this semi-dry process, namely, using anaqueous salt solution on a developing machine, this has thejg'reatadvantage over the ordinary semi-dry developer with adevelopingmachine in that the developer used is merely the solution ofsodium acetateor potassium sulphate or the like which 'has the propertyof keeping indefinitely and does not deteriorate like the ordinarydevelopers which contain readily oxidisable or otherwise unstablesubstances. If, however, it is desired for any reason tofuse a developercontaining an alkali or to develop under alkaline conditions, this mayalso bedone according to the present in- I vention, as thel; compoundscapable of coupling been referred to; Also, for example, it may bedesired to dilute the couplingcomponent, such T,

as p-naphthol, with"an inert substance such as starch or dextrinr.Alternatively, other substances m ay be mixed with the couplingcompovnent in order to increase thespee'd of coupling, sodiumtartrate .being asuitable substance for this purpose. Furthermore, the coupling componentmay be any of the well-known coupling components, such as a phenol orbase, examples being p-naphthol or phloroglucinol.

The followingexamples illustrate how the invention may be carried out inpractice, but it is obvious that the invention is capable of a greatvariety ofmethods of application and is in no way limited ,to the.details given in these examples:

Example 1.The paper is coated witha solution of 60grams of zincchloride, double salt of 5-benzoyl-amino-1:4-diethoxy-2-diazonlumchloride, 30 grams of aluminium sulphate made up to 1000 cc. 'with.water and dried. After drying. the paper is dusted over. the entiresensitive surface with a powder composed of 60 grams of flour and -l0grams of phloroglucinol.

excess of powder removed by The paper. may then be stored for aconsiderable, length of vtime before exposure to light and de-'velopment. After exposure to light the paper can be developed either byexposure to steam or by'the gelatine methodalready herein de--scribed,-or by the semi-drymeth od; A suitable developer I for.development by the semi-dry method is one containing- 100' grams ofsodium acetate crystals, and 2- grams of tartaric acid in 1000 cc;offwater; It will be seen that this developer is one which will keepindefinitely. Example 2. -The paper is coated with a lightvsensitiyelayer as described in Example 1 and drieda After drying', the paper isdusted over the entire sensitive, surface with a powder composed 'of 130gramsfof flour; 1!) grams "of phloroglucinol and soggramsoffsodium'benz'oate- After dusting with the pow nflthepowder iswellrubbed on and into the surface of the paper and excess of powder removedby'brushing. The paper may then, be stored foria considerable length oftime before exposure to, light snddevelopment. In this casedevelopmentof' the'ptintban be carried out simply by contact withwater'which'can idvantageous1y be applied in an ordinary developingmachine. Many diazo compounds willcouple ,under neutral or acidconditions at 15.52pm: is far too slow to be of any use in diazotypepapers After dusting with the powder, the powder .Lr well rubbed on andinto the surface of the paper and of this kind, and I declare that whenin my claims I use the words a diazo compound capable of coupling inneutral or acid 'conditions I mean a diazo compound which under neutralor acid conditions will couple with such speed that the diazo compound'and coupling component could not be put together. in the light sensitivelayer without coupling prematurely, either during drying or storage,whether a dehydration has taken place or not. l

What I claim and desire to secure by Letters Patent is: v I v r 1. As anew article of manufacture, a lightsensitive element comprising acarrier coated with a dry, light-sensitive-layer containingadiazocompound capable of coupling when treated with a coupling component andmoisture in the absence of alkaline substances,- said element car-*rjying, adhered to its surface in the form of a dry powder or dust, acoating containing the coupling component. 1

/ 2'. As a new article, of manufacture, a lightsensitive elementcomprising acarrier coated with a dry, light-sensitive layer containinga diazo compound capable'of coupling when treated with a'coupling-component and moisture in the,

absence of alkaline substances, said element carsensitive elementcomprising a -carrier coated with a dry, light-sensitive layercontainingadiazo compound capable of coupling when treated with a couplingcomponent and moisture in the absence of alkaline substances, saidelement carrying, adhered to its surface in the form of a dry powderordust, a coating containing the coupling component, .the article alsocontaining a hydrated salt capable of liberating moisture.

4. As a new article of manufacture, acarrier coated with a dry,light-sensitive layer containing a diazo compoundcapable of couplingwhen treated with a coupling component and moisture in the absence ofalkaline substances, said lightsensitive layer carrying, adhered to itssurface in the form of a dry powder or dust, a coating containing thecoupling component.

5. A process for preparing diazotype photographic papers by coating apaper with a light-sensitive layer containing a diazo compound capableof coupling when treated with a coupling component and moisture in theabsence of alkaline substances, drying the paper, and subsequentlycoating the paper with a substantially dry coupling component so that itadheres to thejsurface of the sensitive layer, exposing the paper tolight behind the pattern it is desired to reproduce, andsubsequentlydeveloping by treatment with moisture.

6. A process for preparing diazotype photographic prints by coating apaper with a lightsensitive layer containing a diazo compound capable ofcoupling when treated with a coupling component and moisture in theabsence oi. alkaline substances, drying the paper, subsequently dustingthe paper with a coupling component so that it adheres to the surface ofthe sensitive layer, exposing the paper to light behind the pattern itis desired toreproduce, and subsequently developing by treatment withmoisture.

7. A process for preparing diazotype photographic prints by coatingapaper with a lightsensitive layer containing a diazo compound capableof coupling when treated with acoupling component and moisture in theabsence of alkaline substances, drying the paper, subsequently dustingthe paper with a coupling component so that it adheres to the surface ofthe sensitive f layer, exposing the paper to light behindthe pattern itis desired to reproduce, and subsequently developing by treatment withwater vapour at an elevated temperature.

8. A process of developing diazotype photographic prints by coating apaper with a lightsensitive layer containing a diazo compoun'dcapable ofcoupling when treated with a, coupling 1 component and moisture in theabsence of alkaline substances, drying the paper, subsequently dustingthe paper with a coupling component so that it adheres to the surface ofthe sensitive layer, exposing the paper to light behind the patf tern itis desired to reproduce, and subsequently developing by applying, in adeveloping machine, an aqueous solution of a the line from running. M

9. A process of developing diazotype photographic prints by coating apaper with a lightneutral salt to prevent sensitive layer containing adiazo compound capable of coupling when treated with a couplingcomponent and moisture'in the absence of alkaline substances, drying thepaper, subsequently dusting the paper with a coupling component so thatit adheres tothe surface of the sensitive layer, exposing the paper tolight behind the pattern it is desired to reproduce, and subsequently.developing by applying in a developingmachine an aqueous solution of acoupling accelerator.

WERNER PAUL LEUCH.

